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G tolerance vis-à-vis pressure-distension and pressure-flow relationships of leg arteries
KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).ORCID iD: 0000-0001-6361-8965
KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
2012 (English)In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 112, no 10, 3619-3627 p.Article in journal (Refereed) Published
Abstract [en]

During increased gravitoinertial (G) load in the head-to-foot direction, pressures in dependent vascular beds are commonly raised to levels capable of distending precapillary vessels, which, in turn, may reduce arterial pressure, and hence compromise the capacity to withstand G load (G tolerance). We hypothesized that distensibility in precapillary leg vessels would be lower in a group of subjects possessing high G tolerance (H; n = 7; relaxed G tolerance = 6.6 ± 0.8 G) than in a group with low G tolerance (L; n = 8; G tolerance = 3.9 ± 0.3 G). The groups were matched with regard to gender, age, weight, height, and resting arterial pressure. Arterial pressure-distension and pressure-flow experiments were performed with the subject supine in a pressure chamber with a lower leg protruding to the outside. Increased intravascular pressure in the blood vessels of the outside leg was accomplished by stepwise increasing chamber pressure to 240 mmHg. Diameter and flow in the posterior tibial artery were measured by ultrasonographic/Doppler techniques. Pressure-induced increments in arterial diameter and flow were more pronounced (p < 0.03) in the L (14.1 ± 4.2% and 32 ± 21 ml/min respectively) than in the H (1.7 ± 5.0% and 1.6 ± 25 ml/min) group, and the pressure thresholds at which these increments commenced were lower (by 52 and 48 mmHg, respectively) in the L than in the H group (p < 0.04). Negative correlations were observed between G tolerance and the increments in diameter and flow (p < 0.02). Thus, the wall stiffness of precapillary leg vessels is greater in individuals with high relaxed G tolerance; whether a causal relationship exists remains to be established.

Place, publisher, year, edition, pages
2012. Vol. 112, no 10, 3619-3627 p.
Keyword [en]
Acceleration, Arterial stiffness, Distensibility, G-level tolerance, Precapillary vessels, Total peripheral resistance
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URN: urn:nbn:se:kth:diva-93148DOI: 10.1007/s00421-012-2349-1ISI: 000308646000018ScopusID: 2-s2.0-84868513803OAI: diva2:515199

QC 20150629

Available from: 2012-04-12 Created: 2012-04-12 Last updated: 2015-06-29Bibliographically approved

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Eiken, OlaSundblad, PatrikKölegård, Roger
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Environmental Physiology (Closed 20130701)
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